Accident Overview
Following an engine failure, the pilot had a limited choice of terrain for landing. The aircraft touched down hard and subsequently slid into trees. The circumstances of the failure prompted a detailed examination of the engine components.
Metallurgical Examination
A metallurgical examination of the engine revealed that the shaft on the oil pump drive gear, part number 538609, had failed due to fatigue. Evidence of heavy wear was found on the shaft, which coincided with a foreign metallic smear composed of aluminum on the surface of the oil. Despite this smear, analysis of the oil indicated no contamination.
Engine History
Review of the engine log revealed that it had received major repair on several occasions. Among the noted repairs was one instance where a broken piston was addressed.